The purpose of the BCT-3603-X01 is to use with the development board, BCE-GENTrx32-002. It breaks out the module's (BM3603-0x-1) pins and add an antenna to make the development easier.
The BC3603 is a bidirectional OOK/GFSK high performance RF transceiver IC from Holtek that operates in the license-free 315MHz, 433MHz, 470MHz, 868MHz, and 915MHz ISM (Industrial, Scientific and Medical) bands.